I couldn't tell you. The difficult part of the quest chain is:
https://www.wowhead.com/quest=29194/through-a-glass-darkly#comments
There's a boss at the last part of that quest you have to solo. It's extremely difficult and always has been. The boss spams a shadowbolt thingy and it will literally two shot you. I had to spec resto just to stay alive and it was a real struggle. It took me like 20 attempts until I got it.
From what I read in the comments of the quest it looks like it is different for each class. Sounds like mages, for example, can spell steal a shield off the boss. So maybe you can do it. Just don't expect it to be easy. And if it is possible for a mage keep in mind that you may have to change your spec to give yourself more survivability to be able to do it.
Just a thought looking at mage talents. Maybe you can use the Mana Shield talent as arcane to spam a shield to protect you from the boss. When you run out of mana you get a buff that restores your Mana and gives you a crap ton of haste. So I feel like you could have 100% uptime on your Mana Shield. Even with that though I feel like the boss would still be hitting you for 1k-2k per shadowbolt thingy. You'd probably still have to do something to heal yourself. Maybe bandages and healing pots would be enough... Maybe.
Also, I never considered shadow resist gear. If shadow resist gear still works that might be just the thing you need. If you can cut the damage of his twilight bolt by 25-50% you might not even take any damage at all with your Mana Shield up.